Blown sundown 3000d

[KTMrida4life]

Have a blown Sundown 3000 Im trying to fix for a friend. He ran it at 1/8th ohm (.125) and it blew in short order.

OK, so far what Ive figured out.. a few power supply fets are burnt, and a few output fets look OK but measure shorted. Going to replace all of them except the 2 fets in the middle on each side which I believe are voltage regulators right?

So, besides replacing this obvious stuff

2 output drivers IRS21844STRPBF
12 output fets IRFP360LCPBF
16 power supply fets IRFP064NPBF
All of the power supply gate resistors (red/red/black/gold) 22ohm 5% tolerance right? What wattage rating should I get? Resistors are confusing to me.

The output gate resistors all *look* okay and I will measure them once I pull the bad output fets but Im pretty sure they are OK.

So, besides the stuff I listed.. what else should I check or replace? Where are the power supply fet drivers and what would they look like? Is it a big IC? I see a KIA494AP.

Will

[Perry Babin]

The power supply driver transistors may have the circuit board designations of Q7-Q7C and Q8-Q8C (not sure, I don't have any specific information on this amp, a photo of the board may help).

The gate resistors are likely 1/4w. Measure them and buy resistors that are the same physical size.

The L7812 regulators commonly fail when the driver ICs fail.

[KTMrida4life]

These arent photos of the amp Im working on, I found these online. Hopefully they help.





If you click them they should expand.

[ThyDntWntMusic]

the two fets in the middle of each side of the heatsink are rectifier diodes.

you can check them with a multimeter, they could be damaged depending on how much current was pulled through them

[KTMrida4life]

Originally Posted by ThyDntWntMusic

the two fets in the middle of each side of the heatsink are rectifier diodes.

you can check them with a multimeter, they could be damaged depending on how much current was pulled through them

Just checked them and none of the legs are shorted to each other.

Where are the power supply driver transistors on this board?

[KTMrida4life]

OK I think I found them.

Q17, Q27, Q47, and Q49. After some searching I found that they are "2sa1023" but I cant find them for sale anywhere. What is a suitable replacement that is more easily available? Each one goes to 4 power supply fets.



They are circled in green.

Theres another transistor closeby though that I dont know what it does. It is a "2sc1027". What is a suitable replacement for it that is readily available? Might as well replace it too. Its board designation is Q18.

What is the thing circled in orange? I know its a terrible picture, but it is a bigger 3 legged thing. Its board designation is Q24. Says KAY 1381 on it. Should I replace it as well?

[Perry Babin]

If the A1023 transistors are defective, they can be replaced with BD140s.

Q18 and 24 are part of the protection circuit. It's extremely unlikely that they have failed.

Q30 (a KTD1302) may have failed. I don't have any suggestions for a substitute. I doubt that it's critical as long as the transistor is high gain and rated for at least 300ma.

[KTMrida4life]

Originally Posted by Perry Babin

If the A1023 transistors are defective, they can be replaced with BD140s.

Q18 and 24 are part of the protection circuit. It's extremely unlikely that they have failed.

Q30 (a KTD1302) may have failed. I don't have any suggestions for a substitute. I doubt that it's critical as long as the transistor is high gain and rated for at least 300ma.

OK thanks for the info. Did you get my email about the pad that I pulled on the audio board?

[Perry Babin]

I don't think that pad is used.

[KTMrida4life]

Originally Posted by Perry Babin

I don't think that pad is used.

I hope your right! I cant tell if its being used or not.